<template>
	<ul class="list">
		<!--<li 
			class="item" v-for="(item, key) of cities" 
			:key="key" @click="handleLetterClick"
		>-->
		<li 
			class="item" v-for="item of letters" 
			:key="item" @click="handleLetterClick"
			@touchstart="handleTouchStart"
			@touchmove="handleTouchMove"
			@touchend="handleTouchEnd" :ref="item"
		>
			{{item}}
		</li>
	</ul>
</template>

<script>
	export default {
		name: "CityAlphabet",
		
		props: {
			cities: Object
		},
		
		data () {
			return {
				touchStatus: false,
				startY: 0,
				timer: null
			}
		},
		
		updated () {
			this.startY = this.$refs['A'][0].offsetTop
		},
		
		computed: {
			letters () {
				const letters = []
//				console.log('this.cities: ', this.cities)
				for(let i in this.cities){
//					console.log('i: ',i)
					letters.push(i)
				}
				return letters
			}
		},
		
		methods: {
			handleLetterClick (e) {
				this.$emit('change', e.target.innerText);
				console.log(e.target.innerText)
			},
			handleTouchStart () {
				this.touchStatus = true
			},
			handleTouchMove (e) {
				if(this.touchStatus){
					if(this.timer){
						clearTimeout(this.timer)
					}
					this.timer = setTimeout(() => {
//						const startY = this.$refs['A'][0].offsetTop
						const touchY = e.touches[0].clientY -79
	//					const index = Math.floor((touchY - startY) / 20);
						const index = Math.floor((touchY - this.startY) / 20);
						if(index >=0 && index < this.letters.length){
							this.$emit('change', this.letters[index])
						}
					}, 16)				
//					console.log(startY);
				}
			},
			handleTouchEnd () {
				this.touchStatus = false
			}
		}
	}
</script>

<style lang="stylus" scoped>
	@import '~@/assets/styles/varibles.styl'
	.list
		position: absolute
		top: 1.58rem
		right: 0
		bottom : 0
		width: .4rem
		display: flex
		flex-direction: column
		justify-content: center
		.item
			line-height: .44rem
			text-align: center
			color: $bgColor
</style>